Ferrite-glass composites have been used to form ferrite cores, rods and toroids, see for example T Yamaguchi et al., Journal of Materials Science 30 (1995) pages 504 to 508 and references therein. K G Brooks et al., Journal of the American Ceramic Society 74 (1991) pages 2513 to 2517 describe a sol-gel technique for producing a lithium zinc ferrite-glass composite. The preparation methods for the ferrite-glass composites have the disadvantage that, during the sintering phase, the risk of shrinkage and cracking at points of stress is high and may lead to a correspondingly high reject rate when preparing magnets with complex shapes or perforations.
T Matsuura, Practical Surface Technologies No 11 (1988) pages 552 to 558 describes photochemically machinable glass ceramics.